CODEWITHSUNDEEP
javabox2dvertexvertices
Morten Høgseth
Morten Høgseth

Reputation: 338

Box2D Vertices in Shapes

I have a polygon shape in Box2D. The shape is a Triangle, wich I expect to have 3 vertices. In fact all shapes that I create will output 8 vertices. Why is this? And if I output the vertex count, that is always the correct amount. I dont want to render unnecessary lines, tough I would like to get the vertex data from the shape.

@Override
public void setShape(Vec2[] vector) {
    // TODO Auto-generated method stub
    super.setShape(vector);

    //A NEW SHAPE
    shape = new PolygonShape();

    //THE TRIANGLES VECTORS
    Vec2[] vec = new Vec2[3];
    vec[0] = new Vec2(10, 0);
    vec[1] = new Vec2(0, 10);
    vec[2] = new Vec2(0, 0);

    //SET THE VERTICES
    shape.set(vec, vec.length);

}

@Override
public void render() {
    // TODO Auto-generated method stub
    super.render();

    //GET THE VERTICES
    Vec2[] vector = shape.m_vertices;

    System.out.print("\n" + "Vertices: " + vector.length);

}

will always output 8. Why?

Upvotes: 0

Views: 1821

Answers (1)

Steven Lu
Steven Lu

Reputation: 43427

The polygon is represented in the original c++ code with a fixed number of 8 vertices, possibly for performance reasons. you are seeing the consequence of this.

The actual vertex count is tracked, so just use that for rendering.

Upvotes: 1

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